Blackjack

Provably fair

Verify fairness

The session's seed decides every card. Its hash was committed before the first hand; the seed is revealed when the session ends. Each round's cards come from HMAC-SHA256 keyed by the seed over the round's number and the bettor's own seed.

Seed hash

dfcebff91176ba60f59acb9b163a9a386f5a919889c4fb0f119a1ddf0bb85d32

Seed

c64a538c33aa22d816a3468e2bbb5dcbdc23c77d9590ca63b9532fe4ea75f7f5 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

83b7e47bf086c21e3325d2b0d5677e4b

Commitment

Batch 61,159, Merkle root 63258f50b94f3c6ada8d5308081f46a4455c4909048b3110b9adfacfafebaae7. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. eb1493decc33a391ca9ac1c71ac6de93ebd1ea4a90070ab34bece75e8a64ea8f
2. eb2ae30f4b18ee594bc9eac9f7cbde9baf13db5e326e3700195b59a76dd00af0

Checked: the seed hash proves into the root.

To check it yourself, take the session's proof:

1. Hash the seed as above and compare it with the seed hash; prove the seed hash into the root with the Merkle path (keccak256, as for every match).
2. For each round: round seed = HMAC-SHA256(key = seed, "degen.house.round.v1" ‖ 0x00 ‖ u64be(length of the bettor's seed) ‖ bettor's seed ‖ u64be(round)).
3. Key ChaCha20 (RFC 8439, zero nonce) with the round seed and read little-endian 64-bit words; a card is the next word below 2⁶⁴ − 1 − ((2⁶⁴ − 1) mod 52), modulo 52.
4. Replay the round's actions with the game's rules: the cards and the payout must match.

The replay plays every hand rebuilt this way on the server from the same data, and marks any that does not rebuild as recorded.